CN114135854A - Method and device for monitoring pollution of heating surface of power station boiler - Google Patents
Method and device for monitoring pollution of heating surface of power station boiler Download PDFInfo
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- CN114135854A CN114135854A CN202111210462.2A CN202111210462A CN114135854A CN 114135854 A CN114135854 A CN 114135854A CN 202111210462 A CN202111210462 A CN 202111210462A CN 114135854 A CN114135854 A CN 114135854A
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- F23J3/00—Removing solid residues from passages or chambers beyond the fire, e.g. from flues by soot blowers
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Abstract
The invention discloses a method for monitoring pollution on a heating surface of a power station boiler, which comprises the following steps: collecting historical operating data of the power station boiler, and calculating a historical heat exchange coefficient or an actual heat exchange quantity of a heating surface of the boiler according to the historical operating data; carrying out interval division on the design load of the power station boiler, and solving the head data average value of historical heat exchange coefficients or actual heat exchange quantity of different load sections as the optimal heat exchange coefficient or optimal heat exchange quantity; obtaining a one-dimensional interpolation function of the load and the optimal heat exchange coefficient or the optimal heat exchange quantity according to each load section and the corresponding optimal heat exchange coefficient or optimal heat exchange quantity; and obtaining a clean factor according to the ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient or the ratio of the actual heat exchange quantity to the optimal heat exchange quantity, and drawing a clean factor curve chart according to the clean factor, the load and the soot blower action so as to realize boiler pollution monitoring. The method can solve the problems that the cleaning factor obtained by the traditional monitoring method according to the design parameter is not real and is influenced by the load.
Description
Technical Field
The invention relates to the technical field of monitoring of dust accumulation and slag bonding degrees of heating surfaces of power station boilers, in particular to a method and a device for monitoring pollution of the heating surfaces of the power station boilers.
Background
At present, a soot blowing system of a power station generally adopts an operation mode of periodically purging each heating surface of a boiler, and although the soot blowing mode is simple, the soot blowing mode has great blindness and uncertainty. The slagging process and ash deposit of each heating surface of the boiler are influenced by a plurality of factors, are not in linear relation with time, and have larger relation with the coal quality characteristics and the load rate of coal used for combustion. When coal with low ash melting point and high ash content is combusted, the slag bonding and ash deposition rate of the heating surface is high, and the conditions of slag bonding and ash deposition can be relieved when the load fluctuation is large or the load is low for a long time. The traditional periodic blowing mode cannot master the actual soot deposition and slag formation conditions of the heating surface, so that the condition of excessive soot blowing of part of the heating surface or insufficient soot blowing of part of the heating surface is easily caused, and the safety and the economical efficiency of unit operation are influenced. Under the current requirement of high fuel flexibility or load flexibility, it is very important to realize intelligent on-demand soot blowing of a power station boiler, and the soot condition of each heating surface must be obtained firstly to realize intelligent on-demand soot blowing, and soot monitoring is the basis of intelligent on-demand soot blowing.
The cleanliness of each heating surface of a boiler is usually measured by a cleanliness factor CF, which is defined as:
in the formula, KsjIs the actual heat transfer coefficient and KlxThe ideal heat exchange coefficient is that CF is more than 0 and less than 1. The larger the CF is, theThe higher the cleanliness of the heating surface of the boiler.
The ideal heat exchange coefficient is usually obtained by adopting design parameter calculation, and then the actual heat exchange coefficient is obtained by calculating according to real-time operation parameters so as to calculate the cleaning factor of the heating surface. However, because the design working condition points of the utility boiler are usually few, and the current power station generally performs forced wide-load operation, the ideal heat exchange coefficient obtained by fitting the design working condition points is greatly different from the actual heat exchange coefficient, so that the cleaning factor is influenced by the boiler load, and when the boiler load is large, the cleaning factor is low, and when the boiler load is small, the cleaning factor is high; and the actual coal type burned by the boiler is different from the designed coal type, so that the ideal heat exchange coefficient obtained based on the design working condition is different from the actual value.
In addition, because of the high furnace temperature, the combustion conditions in the furnace are very complex, which involves high temperature and turbulent two-phase flow accompanied with numerous physicochemical reactions, and the solid phase flow also contains softened viscous particles. In-situ sampling and measurement in the furnace is difficult due to the lack of suitable equipment. The practical modeling test shows that the model effect of the hearth cleaning factor obtained by calculating the actual heat exchange coefficient and the ideal heat exchange coefficient of the hearth is not ideal.
Disclosure of Invention
Aiming at the defects or improvement requirements of the existing calculation method, the invention provides a method and a device for monitoring pollution on a heating surface of a power station boiler based on a big data analysis technology, and can solve the problems that a cleaning factor obtained by a traditional monitoring method according to design parameters is not real and is influenced by load.
Specifically, an embodiment of the present invention provides a method for monitoring pollution on a heating surface of a power station boiler, which is used for monitoring pollution on a convection heating surface, a semi-radiation semi-convection heating surface, or a radiation heat exchange surface, and includes: (1) the step of calculating the cleaning factors of the convection heating surface and the semi-radiation semi-convection heating surface comprises the following steps: step S11, collecting historical operation data of the utility boiler, and calculating the historical heat exchange coefficient of the heating surface of the boiler according to the historical operation data; step S12, carrying out interval division on the design load of the utility boiler, and solving the average value of the head data of the historical heat exchange coefficients of different load sections as the optimal heat exchange coefficient; step S13, obtaining a one-dimensional interpolation function of the load and the optimal heat exchange coefficient according to each load section and the optimal heat exchange coefficient corresponding to the load section; step S14, obtaining a cleaning factor according to the ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient, and drawing a cleaning factor curve chart by the cleaning factor, the load and the soot blower action so that a user can monitor pollution according to the one-dimensional interpolation function and the cleaning factor curve chart; (2) the step of calculating the cleaning factor of the radiation heat exchange surface comprises the following steps: step S21, collecting historical operation data of the utility boiler, and calculating the actual heat exchange quantity of the water-cooled wall of the hearth according to the historical operation data; step S22, carrying out interval division on the design load of the utility boiler, and solving the head data average value of the historical heat exchange quantity of different load sections as the optimal heat exchange quantity; step S23, obtaining a one-dimensional interpolation function of the load and the optimal heat exchange quantity according to each load section and the corresponding optimal heat exchange quantity; and step S24, obtaining a clean factor according to the ratio of the historical heat exchange quantity to the optimal heat exchange quantity, drawing a clean factor curve chart according to the clean factor, the load and the soot blower action, and monitoring pollution by a user according to the one-dimensional interpolation function and the clean factor curve chart.
In one embodiment of the invention, the historical operating data comprises: boiler load, steam side inlet temperature, steam side outlet temperature, steam side inlet pressure, steam side outlet pressure, flue gas side inlet temperature, and flue gas side outlet temperature.
In one embodiment of the present invention, the boiler heat exchanger belonging to the convection heating surface and the semi-radiation semi-convection heating surface comprises: the system comprises an economizer, a low-temperature reheater, a low-temperature superheater, a high-temperature reheater, a high-temperature superheater, a platen superheater and an air preheater; the boiler heat exchanger belonging to the radiant heat exchange surface comprises: and (5) a hearth water-cooled wall.
In one embodiment of the present invention, the flue gas side inlet temperature and the flue gas side outlet temperature are calculated by: and measuring the flue gas temperature from the economizer inlet, the air preheater inlet or the high-temperature reheater outlet, and calculating the inlet flue gas temperature and the outlet flue gas temperature of the high-temperature reheater, the high-temperature superheater and the platen superheater according to a thermal balance method.
In an embodiment of the present invention, the actual heat exchange amount of the furnace water wall is calculated by: q ═ Q (Q)fw-q1sh-q2sh-qrh)*(hww，out-hww，in) (ii) a Wherein Q is the actual heat exchange amount, QfwFor water supply flow, q1shFor desuperheating water of a primary superheater, q2shFor desuperheating water of a secondary superheater qrhDesuperheating water for reheater hww，outAnd hww，inThe enthalpy values of the outlet and the inlet of the water-cooled wall of the hearth are calculated by inquiring water and steam thermodynamic properties IAPWS-IF97 from the outlet temperature, the pressure and the inlet temperature of the water-cooled wall of the hearth and the pressure.
In an embodiment of the present invention, before step S12 and step S22, the method further includes: carrying out data processing on the obtained historical heat exchange coefficient and the actual heat exchange quantity; further included before step S14 and step S24 is: carrying out data processing on the obtained optimal heat exchange coefficient and the optimal heat exchange quantity; the data processing comprises: and (5) cleaning data, and deleting a bad point value and a zero point value.
In one embodiment of the present invention, the interval division of the design load of the utility boiler comprises: and dividing the load section by taking 5% -20% of full load as one load section.
In an embodiment of the present invention, said averaging the header data of the historical heat exchange coefficients of different load segments as the optimal heat exchange coefficient includes: taking 5% -20% of the maximum historical heat exchange coefficient in the corresponding load section as the head data; the step of calculating an average value of the header data of the historical heat exchange amount of different load segments as an optimal heat exchange amount comprises: and taking 5% -20% of the maximum actual heat exchange quantity in the corresponding load section as the head data.
In one embodiment of the invention, when the pressure of the steam side inlet of a certain stage of heat exchanger is lost, the pressure of the steam side outlet of the previous stage of heat exchanger is preferentially used for substitution, and the pressure drop of the previous stage of heat exchanger under the working condition of corresponding load on a thermodynamic calculation book is subtracted from the pressure of the inlet of the previous stage of heat exchanger for substitution; when the pressure of the steam side outlet of a certain stage of heat exchanger is lacked, the pressure of the steam side inlet of the next stage of heat exchanger is preferentially used for replacement, and the pressure drop of the stage of heat exchanger under the working condition of corresponding load on the thermodynamic calculation book is subtracted from the pressure of the steam side inlet of the current heat exchanger for replacement.
In addition, the embodiment of the invention provides a pollution monitoring device for a heating surface of a power station boiler, which comprises: the heat exchange coefficient or heat exchange quantity calculation module is used for acquiring historical operating data of the power station boiler and calculating the historical heat exchange coefficient or actual heat exchange quantity of the heating surface of the boiler according to the historical operating data; the optimal heat exchange coefficient or optimal heat exchange quantity obtaining module is used for carrying out interval division on the design load of the power station boiler and solving the head data average value of the historical heat exchange coefficients or the actual heat exchange quantities of different load sections as the optimal heat exchange coefficient or optimal heat exchange quantity; an interpolation function obtaining module, configured to obtain a one-dimensional interpolation function of the load and the optimal heat exchange coefficient or the optimal heat exchange amount according to each load segment and the optimal heat exchange coefficient or the optimal heat exchange amount corresponding to the load segment; and the cleaning factor curve drawing module is used for obtaining a cleaning factor according to the ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient or the ratio of the actual heat exchange quantity to the optimal heat exchange quantity, and drawing a cleaning factor curve according to the cleaning factor, the load and the soot blower action.
As can be seen from the above, the above solution contemplated by the present invention may have one or more of the following advantages compared to the prior art:
(1) the actual heat exchange coefficient of each historical time interval of the heating surface is obtained by calculation according to the physical property parameters of the heating surface of the boiler, and the head data average value of the historical heat exchange coefficient of each load interval is used as an ideal heat exchange coefficient, so that the cleaning factor is obtained by calculation, and the problems that the cleaning factor obtained according to design parameters is not true and is influenced by loads can be solved;
(2) the flue gas temperature and the corresponding steam temperature are measured from the inlet of the economizer or the inlet of the air preheater, and the inlet and outlet flue gas temperatures of other semi-radiation semi-convection heat exchange surfaces in the hearth are calculated according to the heat balance principle, so that the problems of difficult on-site sampling and measurement in the furnace due to high temperature of the hearth and very complex combustion working conditions in the furnace can be solved;
(3) load section division is carried out by taking 5% -20% of the maximum value of the design load of the power station boiler as a load section, so that enough intervals of the load section can be ensured, the fitted interpolation function is ensured to be accurate enough, and the complex data calculation caused by the division of too many load section areas is avoided; and taking 5% -20% of the maximum historical heat exchange coefficient or the actual heat exchange amount in the corresponding load section as the head data, and ensuring the accuracy of calculating the optimal heat exchange coefficient or the optimal heat exchange amount data.
Other aspects and features of the present invention will become apparent from the following detailed description, which proceeds with reference to the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIGS. 1 and 2 are flow charts of a method for monitoring pollution on a heating surface of a utility boiler according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of calculating an ideal heat transfer coefficient based on design parameters according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating calculation of an ideal heat transfer coefficient based on a historical optimal heat transfer coefficient according to an embodiment of the present invention;
FIG. 5 is a graph illustrating a high temperature superheater cleaning factor calculated based on design parameters according to an embodiment of the present invention;
FIG. 6 is a graph illustrating a high temperature superheater cleaning factor calculated based on a historical optimal heat transfer coefficient according to an embodiment of the present invention;
FIG. 7 is a graph illustrating a furnace cleaning factor calculated based on heat transfer coefficients according to an embodiment of the present invention;
FIG. 8 is a graph illustrating a hearth cleaning factor calculated based on heat exchange capacity according to an embodiment of the present invention;
FIG. 9 is a schematic structural diagram of a pollution monitoring device for a heating surface of a utility boiler according to an embodiment of the present invention.
Description of the reference numerals
S11-S14, S21-S24: monitoring pollution on the heating surface of the power station boiler;
30: a pollution monitoring device for the heating surface of the power station boiler; 301: a heat exchange coefficient or heat exchange amount calculating module; 302: obtaining a module by the optimal heat exchange coefficient or the optimal heat exchange quantity; 303: an interpolation function obtaining module; 304: and a cleaning factor curve chart drawing module.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The invention will be described in connection with embodiments with reference to the drawings.
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments should fall into the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the method is simple. The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be noted that the division of the embodiments of the present invention is only for convenience of description and should not be construed as a limitation, and features of various embodiments may be combined and referred to each other without contradiction.
[ first embodiment ] A method for manufacturing a semiconductor device
As shown in fig. 1 and fig. 2, an embodiment of the present invention provides a method for monitoring pollution on a heating surface of a utility boiler, which is used for monitoring pollution on a convection heating surface, a semi-radiation semi-convection heating surface, or a radiation heat exchange surface, and includes: (1) the step of calculating the cleaning factors of the convection heating surface and the semi-radiation semi-convection heating surface comprises the following steps: step S11, collecting historical operation data of the utility boiler, and calculating the historical heat exchange coefficient of the heating surface of the boiler according to the historical operation data; step S12, carrying out interval division on the design load of the utility boiler, and solving the average value of the head data of the historical heat exchange coefficients of different load sections as the optimal heat exchange coefficient; step S13, obtaining a one-dimensional interpolation function of the load and the optimal heat exchange coefficient according to each load section and the optimal heat exchange coefficient corresponding to the load section; step S14, obtaining a cleaning factor according to the ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient, and drawing a cleaning factor curve chart by the cleaning factor, the load and the soot blower action so that a user can monitor pollution according to the one-dimensional interpolation function and the cleaning factor curve chart; (2) the step of calculating the cleaning factor of the radiation heat exchange surface comprises the following steps: step S21, collecting historical operation data of the utility boiler, and calculating the actual heat exchange quantity of the water-cooled wall of the hearth according to the historical operation data; step S22, carrying out interval division on the design load of the utility boiler, and solving the head data average value of the historical heat exchange quantity of different load sections as the optimal heat exchange quantity; step S23, obtaining a one-dimensional interpolation function of the load and the optimal heat exchange quantity according to each load section and the corresponding optimal heat exchange quantity; and step S24, obtaining a clean factor according to the ratio of the historical heat exchange quantity to the optimal heat exchange quantity, drawing a clean factor curve chart according to the clean factor, the load and the soot blower action, and monitoring pollution by a user according to the one-dimensional interpolation function and the clean factor curve chart.
The boiler heat exchanger belonging to the convection heating surface and the semi-radiation semi-convection heating surface comprises the following components: the system comprises an economizer, a low-temperature reheater, a low-temperature superheater, a high-temperature reheater, a high-temperature superheater, a platen superheater and an air preheater; boiler heat exchangers belonging to radiant heat exchange surfaces comprise, for example: and (5) a hearth water-cooled wall.
Further, the mentioned historical operating data includes, for example: boiler load, steam side inlet temperature, steam side outlet temperature, steam side inlet pressure, steam side outlet pressure, flue gas side inlet temperature, and flue gas side outlet temperature.
Furthermore, for the operation parameters of the semi-convection heating surfaces such as the high-temperature reheater, the high-temperature superheater and the platen superheater in the step 1, namely the inlet and outlet flue gas temperature, due to the high temperature of the hearth, the combustion working condition in the furnace is very complex, and the on-site sampling and measurement in the furnace are difficult. In one embodiment, the inlet and outlet flue gas temperature is estimated according to the heat balance, for example, the flue gas temperature and the corresponding steam temperature are measured from the economizer inlet or the air preheater inlet, and the inlet and outlet flue gas temperature of the semi-radiative semi-convective heat exchange surface is estimated according to the heat balance. The basic principle of the thermal equilibrium method is the energy conservation principle, and the heat emitted by the smoke side is equal to the heat absorbed by the working medium side. Flue gas generated by pulverized coal combustion sequentially flows through three semi-radiation semi-convection heating surfaces of a screen type superheater, a high-temperature superheater and a high-temperature reheater. Generally, temperature measuring equipment of a boiler is difficult to work normally for a long time due to high temperature on the flue gas side of a semi-radiation semi-convection heating surface, temperature measuring points are arranged at an outlet of a high-temperature reheater with low temperature, and more temperature measuring points are arranged on the working medium side. Therefore, the enthalpy change of the working medium side of the high-temperature reheater can be calculated according to the operation parameters of the boiler, then the inlet flue gas temperature of the high-temperature reheater, namely the outlet flue gas temperature of the high-temperature superheater, can be calculated according to the energy conservation, the inlet flue gas temperature of the high-temperature superheater, namely the outlet flue gas temperature of the platen superheater can be calculated in the same way, and the inlet flue gas temperature of the platen superheater can be calculated in the same way. Therefore, the temperature data of each heating surface in the furnace can be accurately calculated, and the problem of difficulty in on-site sampling and measuring in the furnace is solved.
Specifically, a semi-radiation semi-convection heating surface, namely a high-temperature superheater (also called a final superheater) and a radiation heating surface, namely a hearth are selected as an embodiment, and the high-temperature superheater is compared by adopting two methods of calculating an ideal heat exchange coefficient by using design parameters and calculating the ideal heat exchange coefficient based on a historical optimal heat exchange coefficient; the method for calculating the cleaning factor of the hearth based on the heat exchange coefficient and the heat exchange quantity is adopted for comparison, and the invention is further explained in detail:
firstly, analyzing the high-temperature superheater and the hearth heating surface of the 350MW boiler
1. For a semi-radiation semi-convection heating surface-high-temperature superheater, two clean factor calculation methods are as follows:
(1) calculating to obtain the actual heat exchange quantity Q of the high-temperature superheater according to the following formula, and then calculating to obtain the actual heat exchange coefficient K of the high-temperature superheater according to the area of the heat exchange surface and other operation parameterssj；
Q＝D(h″-h′)/Bj
In the formula, D is the flow of the working medium kg/h; h ', h' is the enthalpy of steam at the inlet and the outlet of the heating surface, and kJ/kg; b isjFor the calculation of the fuel quantity, kg/h.
(2) And calculating the inlet and outlet flue gas temperature of the high-temperature superheater according to a thermal equilibrium method. The formula is as follows, the inlet flue gas temperature of the high-temperature reheater, namely the outlet flue gas temperature of the high-temperature superheater, is calculated according to the known working medium temperature and the outlet flue gas temperature of the high-temperature reheater. The inlet flue gas temperature of the high-temperature superheater is calculated by the known working medium temperature and the calculated inlet flue gas temperature of the high-temperature reheater,
Qflue gas＝QWorking medium
In the formula (I), the compound is shown in the specification,
is the heat retention coefficient; h 'and H' are respectively the enthalpy values of smoke at the inlet and the outlet of the heating surface, kJ/kg. The enthalpy value of the flue gas is obtained from the temperature of the inlet and outlet flue gas.
(3) The inlet and outlet steam enthalpy can be found according to the inlet and outlet steam temperature and pressure of the heating surface.
Ksj＝Q·Bj/(A·Δt)
Wherein A is the heat transfer area of the heating surface, m2(ii) a Delta t is the heat transfer temperature and pressure, DEG C. And delta t is the difference between the temperature of the flue gas side inlet and the temperature of the working medium side outlet.
(4) And carrying out data processing on the actual heat exchange coefficient.
Specifically, the data processing includes data cleaning, the actual heat exchange coefficient data cleaning is to process a bad point value and a zero point value of the data, the obtained industrial data is not clean due to damage of a measuring point, shutdown of a unit, system restart and the like, and some abnormal values cannot be completely eliminated by early data preprocessing, so that obvious abnormal values need to be deleted after the actual heat exchange coefficient or the actual heat exchange quantity is calculated.
(5) The ideal heat exchange coefficient of the high-temperature superheater is calculated by two methods respectively.
Calculating an ideal heat exchange coefficient of the high-temperature superheater based on design parameters. According to the parameters given by the 350MW boiler design manual, under the loads of the 50BRL (175MW), the 75BRL (262.5MW) and the 100BRL (350MW) boilers respectively, the corresponding ideal heat exchange coefficients are calculated according to the method for calculating the actual heat exchange coefficients, and a graph for calculating the ideal heat exchange coefficients based on the design parameters is obtained by fitting, as shown in FIG. 2. The cleaning factor is obtained from the ratio of the actual heat transfer coefficient to the ideal heat transfer coefficient, and a cleaning factor graph based on design parameters is obtained from the cleaning factor, the boiler load, and the high-temperature superheater soot blower, as shown in fig. 4, in which the solid line represents the cleaning factor and the dotted line represents the boiler load (the boiler load has been normalized, where 350MW is '1').
Secondly, the ideal heat exchange coefficient is calculated based on the historical optimal heat exchange coefficient. Grouping the calculated actual heat exchange coefficients according to the load range, for example, dividing the load by taking 5% -20% of the full load as a load segment, preferably, dividing the load into 7 groups: 175-200 MW, 200-225 MW … … 325-350 MW, so as to ensure that the fitted interpolation function is accurate enough, and simultaneously avoid the complex data calculation caused by dividing too many load section areas. For example, 5% -20% of the maximum actual heat exchange coefficient in the corresponding load section is taken as the head data, the average value of the head data is taken as the ideal heat exchange coefficient, preferably, the average value of the first 10% of the actual heat exchange coefficients in 7 groups is respectively taken, and therefore a graph for calculating the ideal heat exchange coefficient based on the historical optimum heat exchange coefficient is obtained according to the fitting of the 7 ideal heat exchange coefficients corresponding to the 7 load sections, as shown in fig. 3, and the accuracy of calculating the optimum heat exchange coefficient is guaranteed.
The cleaning factor is obtained from the ratio of the actual heat transfer coefficient to the ideal heat transfer coefficient, and a cleaning factor graph based on design parameters is obtained from the cleaning factor, the boiler load, and the high temperature superheater soot blower, as shown in fig. 5, in which the solid line represents the cleaning factor and the dotted line represents the boiler load (the boiler load has been normalized, where 350MW is '1').
2. For a radiation heating surface hearth, two clean factor calculation methods are as follows:
(1) calculating an actual heat exchange coefficient and an actual heat exchange quantity of the hearth according to the operation parameters;
(2) the actual heat exchange coefficient or the actual heat exchange quantity is subjected to data processing in the same way as the heat exchange coefficient, and the details are not repeated herein;
(3) and respectively calculating the furnace cavity cleaning factor by using methods based on ideal heat exchange coefficients and historical heat exchange quantity.
Calculating a furnace hearth cleaning factor based on the heat exchange coefficient. According to parameters given by a 350MW boiler design manual, corresponding ideal heat exchange coefficients are calculated under 50BRL (175MW), 75BRL (262.5MW) and 100BRL (350MW) boiler loads respectively, an ideal heat exchange coefficient graph calculated based on the design parameters is obtained through fitting, a cleaning factor is obtained according to the ratio of the actual heat exchange coefficient to the ideal heat exchange coefficient, and a hearth cleaning factor graph calculated based on the heat exchange coefficient is obtained according to the cleaning factor and the boiler load, as shown in FIG. 6, wherein a solid line represents the cleaning factor, and a dotted line represents the boiler load (the boiler load is normalized, wherein the 350MW is '1').
Secondly, the invention calculates the hearth cleaning factor based on the hearth heat exchange quantity. The calculated actual heat exchange amount is grouped according to the boiler load range, for example, the load section is divided by 5% -20% of the full load, and preferably, the load is divided into 7 groups: 175-200 MW, 200-225 MW … … 325-350 MW, respectively take the first 5% -20%, preferably, the average value of the first 10% of the actual heat exchange coefficient in 7 groups, and take the average value as the ideal heat exchange amount, so that the optimal heat exchange amount based on history is obtained according to 7 ideal heat exchange amount fits corresponding to 7 load points. Thus, the furnace cleaning factor is obtained from the ratio of the actual heat exchange amount to the ideal heat exchange amount, and a graph based on the heat exchange amount cleaning factor is obtained according to the cleaning factor, the boiler load, and the furnace soot blower, as shown in fig. 7, in which the solid line represents the furnace cleaning factor and the dotted line represents the boiler load (the boiler load is normalized, where 350MW is '1').
Comparative analysis
As can be seen from the two high-temperature superheater cleaning factor graphs of FIG. 4 and FIG. 5, the cleaning factor in the cleaning factor graph based on design parameters is significantly large, which indicates that the difference between the ideal heat exchange coefficient calculated by the method and the actual heat exchange coefficient is large, but the cleaning factor in the cleaning factor graph based on the historical optimal heat exchange coefficient basically satisfies the definition of the cleaning factor of 0-1. In addition, in a graph (namely figure 5) based on the historical optimal heat exchange coefficient cleaning factor, the cleaning factor rises in different amplitudes during soot blowing action, and the effectiveness of the model is proved. And the cleaning factor rises first and then falls down wholly in a soot blowing period of the soot blower, and does not fluctuate up and down, so that the soot monitoring and modeling effect is better.
As can be seen from the two hearth cleaning factor graphs of FIG. 6 and FIG. 7, the hearth cleaning factor calculated based on the heat exchange coefficient in FIG. 6 has a severe change range and an unobvious regularity, which indicates that the modeling effect of calculating the hearth cleaning factor based on the heat exchange coefficient is poor and the hearth fouling condition cannot be reflected. And fig. 7 adopts the improved cleaning factor calculated based on the heat exchange amount, the cleaning factor rises first and then falls integrally in one soot blowing period of the soot blower, and no fluctuation occurs, which indicates that the soot monitoring modeling effect is better.
In addition, it is worth mentioning that when the pressure of the steam side inlet of a certain stage of boiler heat exchanger is lost, the pressure of the steam side outlet of the previous stage of heat exchanger is preferentially used for replacement, and the pressure drop of the previous stage of heat exchanger under the working condition of corresponding load on the thermodynamic calculation book is subtracted from the pressure of the inlet of the previous stage of heat exchanger for replacement; when the pressure of the steam side outlet of a certain stage of heat exchanger is lacked, the pressure of the steam side inlet of the next stage of heat exchanger is preferentially used for replacement, and the pressure drop of the stage of heat exchanger under the working condition of corresponding load on a thermodynamic calculation book is subtracted from the pressure of the steam side inlet of the current heat exchanger for replacement, so that the completeness and the accuracy of the implementation of the method are guaranteed.
In summary, the embodiment of the invention provides a method for monitoring pollution on a heating surface of a power station boiler, which includes the steps of calculating actual heat exchange coefficients of the heating surface in various historical time periods according to physical parameters of the heating surface of the boiler, and calculating a cleaning factor by using a head data average value of the historical heat exchange coefficients of the load sections as an ideal heat exchange coefficient, so that the problems that the cleaning factor obtained according to design parameters is not real and is influenced by load can be solved; the flue gas temperature and the corresponding steam temperature are measured from the inlet of the economizer or the inlet of the air preheater, and the inlet and outlet flue gas temperatures of other semi-radiation semi-convection heat exchange surfaces in the hearth are calculated according to the heat balance principle, so that the problems of difficult on-site sampling and measurement in the furnace due to high temperature of the hearth and very complex combustion working conditions in the furnace can be solved; load section division is carried out by taking 5% -20% of the maximum value of the design load of the power station boiler as a load section, so that enough intervals of the load section can be ensured, the fitted interpolation function is ensured to be accurate enough, and the complex data calculation caused by the division of too many load section areas is avoided; and taking 5% -20% of the maximum historical heat exchange coefficient or the actual heat exchange amount in the corresponding load section as the head data, and ensuring the accuracy of calculating the optimal heat exchange coefficient or the optimal heat exchange amount data.
[ second embodiment ]
As shown in FIG. 9, a second embodiment of the present invention provides a pollution monitoring device 30 for a heating surface of a utility boiler, comprising: the system comprises a heat exchange coefficient or heat exchange quantity calculation module 301, an optimal heat exchange coefficient or optimal heat exchange quantity obtaining module 302, an interpolation function obtaining module 303 and a cleaning factor curve chart drawing module 304.
The heat exchange coefficient or heat exchange amount calculation module 301 is configured to collect historical operation data of the utility boiler, and calculate a historical heat exchange coefficient or an actual heat exchange amount of the heating surface of the boiler according to the historical operation data. The optimal heat exchange coefficient or optimal heat exchange amount obtaining module 302 is configured to perform interval division on the design load of the utility boiler, and obtain an average value of the header data of the historical heat exchange coefficients or the actual heat exchange amounts of different load segments as an optimal heat exchange coefficient or an optimal heat exchange amount. The interpolation function obtaining module 303 is configured to obtain a one-dimensional interpolation function of the load and the optimal heat exchange coefficient or the optimal heat exchange amount according to each load segment and the optimal heat exchange coefficient or the optimal heat exchange amount corresponding to the load segment. The cleaning factor graph drawing module 304 is configured to obtain a cleaning factor according to a ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient or a ratio of the actual heat exchange amount to the optimal heat exchange amount, and draw a cleaning factor graph according to the cleaning factor, the load, and the soot blower operation.
The method of monitoring the pollution on the heating surface of the utility boiler 20 according to the second embodiment of the present invention is as described in the first embodiment, and therefore, will not be described in detail herein. Optionally, each module and the other operations or functions in the second embodiment are respectively for implementing the method for monitoring pollution on the heating surface of the power station boiler described in the first embodiment, and the beneficial effects of this embodiment are the same as those of the first embodiment, and are not described herein for brevity.
In addition, it should be understood that the foregoing embodiments are merely exemplary illustrations of the present invention, and the technical solutions of the embodiments can be arbitrarily combined and collocated without conflict between technical features and structural contradictions, which do not violate the purpose of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed system, apparatus and/or method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units/modules is only one logical division, and there may be other divisions in actual implementation, for example, multiple units or modules may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units/modules described as separate parts may or may not be physically separate, and parts displayed as units/modules may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the units/modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In addition, each functional unit/module in the embodiments of the present invention may be integrated into one processing unit/module, or each unit/module may exist alone physically, or two or more units/modules may be integrated into one unit/module. The integrated units/modules may be implemented in the form of hardware, or may be implemented in the form of hardware plus software functional units/modules.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A pollution monitoring method for a heating surface of a power station boiler is characterized by being used for monitoring pollution of a convection heating surface, a semi-radiation semi-convection heating surface or a radiation heat exchange surface, and comprising the following steps of:
(1) the step of calculating the cleaning factors of the convection heating surface and the semi-radiation semi-convection heating surface comprises the following steps:
step S11, collecting historical operation data of the utility boiler, and calculating the historical heat exchange coefficient of the heating surface of the boiler according to the historical operation data;
step S12, carrying out interval division on the design load of the utility boiler, and solving the average value of the head data of the historical heat exchange coefficients of different load sections as the optimal heat exchange coefficient;
step S13, obtaining a one-dimensional interpolation function of the load and the optimal heat exchange coefficient according to each load section and the optimal heat exchange coefficient corresponding to the load section;
step S14, obtaining a cleaning factor according to the ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient, and drawing a cleaning factor curve chart by the cleaning factor, the load and the soot blower action so that a user can monitor pollution according to the one-dimensional interpolation function and the cleaning factor curve chart;
(2) the step of calculating the cleaning factor of the radiation heat exchange surface comprises the following steps:
step S21, collecting historical operation data of the utility boiler, and calculating the actual heat exchange quantity of the water-cooled wall of the hearth according to the historical operation data;
step S22, carrying out interval division on the design load of the utility boiler, and solving the head data average value of the historical heat exchange quantity of different load sections as the optimal heat exchange quantity;
step S23, obtaining a one-dimensional interpolation function of the load and the optimal heat exchange quantity according to each load section and the corresponding optimal heat exchange quantity;
and step S24, obtaining a clean factor according to the ratio of the historical heat exchange quantity to the optimal heat exchange quantity, drawing a clean factor curve chart according to the clean factor, the load and the soot blower action, and monitoring pollution by a user according to the one-dimensional interpolation function and the clean factor curve chart.
2. The utility boiler heating surface pollution monitoring method of claim 1, wherein the historical operating data includes: boiler load, steam side inlet temperature, steam side outlet temperature, steam side inlet pressure, steam side outlet pressure, flue gas side inlet temperature, and flue gas side outlet temperature.
3. The utility boiler heating surface pollution monitoring method according to claim 2, wherein the boiler heat exchanger belonging to the convection heating surface and the semi-radiation semi-convection heating surface comprises: the system comprises an economizer, a low-temperature reheater, a low-temperature superheater, a high-temperature reheater, a high-temperature superheater, a platen superheater and an air preheater; the boiler heat exchanger that belongs to radiation heat transfer surface includes: and (5) a hearth water-cooled wall.
4. The method of claim 3, wherein the flue gas side inlet temperature and the flue gas side outlet temperature are calculated by: and measuring the flue gas temperature from the economizer inlet, the air preheater inlet or the high-temperature reheater outlet, and calculating the inlet flue gas temperature and the outlet flue gas temperature of the high-temperature reheater, the high-temperature superheater and the platen superheater according to a thermal balance method. .
5. The method of claim 3, wherein the actual amount of heat exchange of the furnace water wall is calculated by:
Q＝(qfw-q1sh-q2sh-qrh)*(hww，out-hww，in)；
whereinQ is the actual heat exchange amount, QfwFor water supply flow, q1shFor desuperheating water of a primary superheater, q2shFor desuperheating water of a secondary superheater qrhDesuperheating water for reheater hww，outAnd hww，inThe enthalpy values of the outlet and the inlet of the water-cooled wall of the hearth are calculated by inquiring water and steam thermodynamic properties IAPWS-IF97 from the outlet temperature, the pressure and the inlet temperature of the water-cooled wall of the hearth and the pressure.
6. The utility boiler heating surface pollution monitoring method according to claim 1, further comprising, before steps S12 and S22: carrying out data processing on the obtained historical heat exchange coefficient and the actual heat exchange quantity; further included before step S14 and step S24 is: carrying out data processing on the obtained optimal heat exchange coefficient and the optimal heat exchange quantity; the data processing comprises: and (5) cleaning data, and deleting a bad point value and a zero point value.
7. The utility boiler heating surface pollution monitoring method of claim 1, wherein the interval division of the design load of the utility boiler comprises: and dividing the load section by taking 5% -20% of full load as one load section.
8. The method of claim 7, wherein the step of averaging the header data of the historical heat transfer coefficients of different load sections as the optimal heat transfer coefficient comprises: taking 5% -20% of the maximum historical heat exchange coefficient in the corresponding load section as the head data; the step of calculating an average value of the header data of the historical heat exchange amount of different load segments as an optimal heat exchange amount comprises: and taking 5% -20% of the maximum actual heat exchange quantity in the corresponding load section as the head data.
9. The method for monitoring pollution on the heating surface of the utility boiler according to claim 3, characterized in that when the pressure at the steam side inlet of a certain stage of heat exchanger is lost, the pressure at the steam side outlet of the previous stage of heat exchanger is preferentially used for substitution, and the pressure drop of the previous stage of heat exchanger under the condition of corresponding load on a thermodynamic calculation book is subtracted from the pressure at the inlet of the previous stage of heat exchanger for substitution; when the pressure of the steam side outlet of a certain stage of heat exchanger is lacked, the pressure of the steam side inlet of the next stage of heat exchanger is preferentially used for replacement, and the pressure drop of the stage of heat exchanger under the working condition of corresponding load on the thermodynamic calculation book is subtracted from the pressure of the steam side inlet of the current heat exchanger for replacement.
10. The utility model provides a power plant boiler heating surface pollution monitoring devices which characterized in that includes:
the heat exchange coefficient or heat exchange quantity calculation module is used for acquiring historical operating data of the power station boiler and calculating the historical heat exchange coefficient or actual heat exchange quantity of the heating surface of the boiler according to the historical operating data;
the optimal heat exchange coefficient or optimal heat exchange quantity obtaining module is used for carrying out interval division on the design load of the power station boiler and solving the head data average value of the historical heat exchange coefficients or the actual heat exchange quantities of different load sections as the optimal heat exchange coefficient or optimal heat exchange quantity;
an interpolation function obtaining module, which obtains a one-dimensional interpolation function of the load and the optimal heat exchange coefficient or the optimal heat exchange quantity according to each load section and the optimal heat exchange coefficient or the optimal heat exchange quantity corresponding to the load section;
and the cleaning factor curve drawing module is used for obtaining a cleaning factor according to the ratio of the historical heat exchange coefficient to the optimal heat exchange coefficient or the ratio of the actual heat exchange quantity to the optimal heat exchange quantity, and drawing a cleaning factor curve according to the cleaning factor, the load and the soot blower action.
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